Technical Field
The present disclosure relates to a light-emitting diode, and more particularly, to a light-emitting diode having a reflective layer.
Description of Related Art
FIG. 1 is a three-dimensional view of a conventional light-emitting diode 100. In FIG. 1, the light-emitting diode 100 has a first type semiconductor layer 110, a light-emitting layer 120, a second type semiconductor layer 130, a current spreading layer 140, a first electrode 150 and a second electrode 160. The light-emitting layer 120 is sandwiched between the first type semiconductor layer 110 and the second type semiconductor layer 130. The current spreading layer 140 covers the second type semiconductor layer 130. The first electrode 150 is positioned on the first semiconductor layer 110, and the second electrode 160 is positioned on the current spreading layer 140.
FIG. 2 is a schematic cross-sectional view of the conventional light-emitting diode 100 along the A-A′ line in FIG. 1. In FIG. 2, the cross-sectional structure positioned on the second type semiconductor layer 130 is shown in detail, and the first type semiconductor layer 110 and the light-emitting layer 120 are omitted. The current blocking layer 170 is positioned on part of the surface of the second type semiconductor layer 130, and the current spreading layer 140 covers the current blocking layer 170 and the second type semiconductor layer 130. The reflective layer 180 is positioned on the current spreading layer 140 and over the current blocking layer 170. Further, the first electrode 150 is positioned on the reflective layer 180.
Referring to FIGS. 1 and 2, when a light B emits from the light-emitting layer 120, the light B may penetrate the second type semiconductor layer 130, the current blocking layer 170 and current spreading layer 140, and then be reflected by the reflective layer 180. However, when the light B goes through the second type semiconductor layer 130, the current blocking layer 170 and the current spreading layer 140, the energy of the light B is absorbed, and becomes a light C with weaker brightness, which reduces the light extraction of the light-emitting diode 100.
On another way, because the reflective layer 180 is usually made of metallic materials and partially exposed out of the light-emitting diode 100, the reflective layer 180 is vulnerable to corrosion from air or water vapor in the environment, resulting in a broken circuit of the light-emitting diode 100 and even the electrical failure.
In addition, in case of the light-emitting diode 100 under overdriving operation, the metallic material of the reflective layer 180 is apt to diffuse into the current spreading layer 140 and increases the surface resistance of the current spreading layer 140, so as to damage the structure of the light-emitting diode 100. Therefore, there is a need for an improved light-emitting diode and a manufacturing method thereof, so as to solve the aforementioned problems met in the art.